give this a shot
Private Sub inboxItem_LinkClicked(sender As Object, e As DevExpress.XtraNavBar.NavBarLinkEventArgs) Handles inboxItem.LinkClicked
Panel1.visible = true
Panel2.visible = false
End Sub
Private Sub outboxItem_LinkClicked(sender As Object, e As DevExpress.XtraNavBar.NavBarLinkEventArgs) Handles outboxItem.LinkClicked
Panel1.visible = false
Panel2.visible = true
End Sub
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Panel1.visible = false
Panel2.visible = false
End Sub
another thing to check is that panel2 is not inside of panel1.